We propose to conduct a placebo-controlled non-inferiority pilot study to evaluate the rate of worsening of intracranial injury patterns after initiation of enoxaparin in TBI patients. Patient enrollment will occur at ETMC, blinded re-reading of CTs will occur at PMH, and administrative/analytical support will occur at UTSW. The study design will be a double-blind, randomized controlled trial in the ETMC Surgical Intensive Care Unit (SICU) consisting of 40 patients per arm. The decision for 80 patients was resource-based, as this is a pilot study. Further, we anticipate the need to contact 3 patients in order to obtain 1 successful recruitment.